DESCRIPTION: Improved glycemic control resulting from intensive diabetes treatment methods, as utilized in the Diabetes Control and Complications Trial, leads to decreased risk for the development and progression of microvascular complications of insulin-dependent diabetes mellitus. However, achieving better glycemic control remains a challenging and often elusive goal. It is increasingly clear from the investigators' own studies and those of others that psychosocial factors, in particular patient negative attitudes about diabetes and its treatment, can be critical impediments to diabetes self-care behaviors. However, little research has been done to develop and test conceptually relevant psychosocial interventions for use with diabetic patients. Therefore, the investigators propose to study whether a psychosocial intervention that is designed to influence patients' negative attitudes leads to better glycemic control. Sixty patients with insulin-dependent diabetes mellitus (IDDM) will be randomly assigned to one of two group treatment conditions: 1) a program of cognitive behavioral therapy (CBT) targeted to attitudinal impediments of improved glycemia; or 2) a control condition in which patients receive an educational program that is valuable for diabetes care, but that should not influence psychosocial factors in and of itself. Both interventions will be carried out under conditions of maximal importance, when patients enter a program to improve their glycemic control and are focused on trying to change their self-care patterns. Patients will be evaluated immediately prior to randomization, immediately after completion of the interventions, and at 6 and 12 month follow-up. The primary outcome will be glycemic control assessed by HbA(1C). Secondary outcomes will include measures of patient adherence and health-related quality of life. The investigators will also examine mechanisms linking the intervention's effectiveness to improved glycemic control, e.g., whether changes in pessimistic attitudes related to IDDM mediate the effect of CBT on HbA(1C). If they find that CBT is effective in terms of improving glycemic control, they plan to evaluate if this intervention can be successfully implemented by certified diabetes educators and be usefully applied in the treatment of patients with non-insulin-dependent diabetes mellitus.